Pretty sure the general consensus is, “it’s the SHAAAAAA, maaaaaan!!!” 
Which is absolutely depressing the hell out of me, beause:

a. Corruption has been done to death in WoW

So how do you feel now that the Word of God states:

“Fargo: So many Warcraft villains are corrupt or possessed. Garrosh? He’s just a bad apple. Everything is a weapon to him. Even the sha.”